1. Field
The disclosure relates to a process for making composite parts. In particular, the disclosure relates to a vacuum resin infusion for making fiber-reinforced resin composite parts.
2. Description of Related Art
Vacuum resin infusion is a process for making high quality composite parts used in the aerospace, automotive, marine, trucking, rail, defense, and other industries. Composite parts manufactured with known vacuum resin processes have a high strength and stiffness, are resistant to fatigue and chemical attack, and are corrosion-free or corrosion-resistant. Such a known vacuum resin infusion process is the controlled atmospheric pressure resin infusion (CAPRI) process. FIG. 1 is a schematic drawing of the known CAPRI process. In this process, as shown in FIG. 1, a reduced pressure vacuum is placed on an inlet reservoir 10. A vacuum pump operating at the exit of a vacuum bag layer 14 reduces the pressure at the outlet to essentially full vacuum to create a driving force between the inlet reservoir and an outlet vacuum reservoir 12. The pressure on the resin in the inlet reservoir pushes the resin into the vacuum bag layer 14 where a preform 16 of dry reinforcing fibers sits on a mold surface with appropriate release plies. Resin entering the vacuum bag layer 14 flows into a resin distribution tube 18 that carries the resin over the preform 16 and over a porous peel ply 20. The resin flows through the peel ply 20 down into the preform, moving from the inlet toward the outlet. During infusion, pressure in the vacuum bag layer will increase from essentially full vacuum to about the pressure of the inlet reservoir. For large composite parts, numerous resin distribution tubes must be used. Where the resin distribution tube contacts the surface of the preform, surface deformation or mark-off occurs because of the vacuum pressure on the resin distribution tube into the preform.
FIG. 2 is a close-up perspective view of a known resin distribution tube 22 used in known resin infusion processes, in which the resin distribution tube 22 sits on the surface of a preform 24, layered with a release material 26 and a flow media 28, and causes deformation of the preform. Such deformation or mark-off not only causes a visual defect in the composite part but also causes a physical distortion of the dry reinforcing fibers in the preform. Such physical distortion can affect the mechanical performance of the composite part, including such mechanical performance properties as tensile properties and compression properties. A known approach used to address the deformation is to attempt to distribute the pressure of the resin distribution tube over a larger area, such as the known apparatus shown in FIG. 3, which shows a front sectional view of a known resin distribution tube 30 that uses a wide base 32 with an opening 34 along the bottom for transfer of resin from the resin distribution tube 30 to a preform 36. However, although the use of a wider area may reduce the pressure in a concentrated area, the deformation or mark-off problem is merely transferred to a wider area because there is still direct contact between the resin distribution tube and the preform.
Accordingly, there is a need for an improved process that does not have the problems associated with known processes and devices.